Convert NWD to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read NWD files and write CATPart, carrying across the exact geometry the NWD file contains.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads Navisworks · Writes CATPart
- Mixed geometry → exact geometry
- C++ / C# APIs
NWD to CATPart at a glance
Navisworks can mix exact solids and facets; CATPart stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| Navisworks (source) | CATPart (target) | |
|---|---|---|
| Full name | Navisworks document and cache files | CATIA V5 Part |
| Standard / owner | Autodesk | Dassault Systèmes |
| File extensions | .nwd, .nwc | .CATPart |
| Geometry | Mostly tessellated, B-Rep for cylinder and elliptical shapes | Exact B-Rep |
| Assemblies / structure | Yes | Part file (assemblies are CATProduct files) |
| PMI | Not imported by 3D InterOp | Semantic and graphical |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from Navisworks to CATPart.
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Preserved
Exact geometryExact B-Rep read from NWD is written to CATPart as exact geometry.
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Changes
Assembly structureCATPart has no native assembly hierarchy. Decide in your application how Navisworks product structure is grouped or flattened before writing.
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Changes
Mostly faceted modelNavisworks models are mainly read as visualization data; exact B-Rep is extracted only for cylinder and elliptical shapes.
Why software vendors add NWD to CATPart conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATPart. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATPart keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATPart directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATPart versions: CATIA V5 R15 to V5-6 R2026.
- Supported NWD input: Navisworks 2011 to 2026 (.nwd and .nwc).
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is a Navisworks (.nwd) file?
NWD is Autodesk Navisworks’ document format, a compact snapshot of a coordination model that combines files from many design tools. NWC files are the cache files Navisworks creates when it opens a native file.
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Target format
What is a CATPart (.CATPart) file?
A CATPart file is a CATIA V5 part: one component with its exact 3D geometry, features and, often, PMI. Assemblies of parts are stored in CATProduct files.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from NWD is written to CATPart; parts stored only as facets stay faceted.
CATPart has no assembly hierarchy, so your application decides how the NWD structure is grouped or flattened before writing.
Mostly not. Navisworks models are read as visualization data; exact B-Rep is extracted only for cylinder and elliptical shapes.
3D InterOp reads Navisworks 2011 to 2026 (.nwd and .nwc).
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
No. 3D InterOp reads NWD but doesn’t write it. To send data back to Navisworks users, write a format Navisworks opens, such as IFC.
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Building software that needs to convert NWD to CATPart?
3D InterOp is an SDK that lets your application read Navisworks and write CATPart alongside 30+ CAD and BIM formats.